Consecutive three-component synthesis of 3-(hetero)aryl-1H-pyrazoles with propynal diethylacetal as a three-carbon building block

A novel consecutive three-component synthesis of 3-(hetero)aryl-1H-pyrazoles via room temperature Sonogashira arylation of propynal diethylacetal used as a propargyl aldehyde synthetic equivalent has been disclosed. The final acetal cleavage-cyclocondensation with hydrazine hydrochloride at 80 °C rapidly furnishes the title compounds in a one-pot fashion.     

Practical synthesis of (Z)-polyaromatic and heteroaromatic vinylacetylenes

[reaction: seet text] Two synthetic routes to several (Z)-polyaromatic and heteroaromatic substituted vinylacetylenes are described. The nature of aryl- or heteroaryl-substituted carboxaldehyde used as starting material dictated the choice of Wittig salt employed. A very attractive way to construct polyaromatic and pyridine-containing enynes is the reaction of polyaromatic and pyridine-containing aldehydes with bromomethyltriphenylphosphonium bromide in the presence of potassium tert-butoxide followed by a Sonogashira desilylation procedure (method B).     

Sonogashira reactions of α- and β-1-ethynyl-2-deoxyribosides: synthesis of acetylene-extended C-nucleosides

An improved practical protocol for the synthesis of both anomers of 1-ethynyl-2-deoxiribosides 1 was developed. The Sonogashira coupling of ethynyldeoxyribosides 1 with various aryl- and heteroaryl halides was carried out under various conditions. It was found that the use of copper-free coupling protocols could reduce the oxidative dimerisation in favour of arylalkynyldeoxyriboside formation.     

Hydrazinoaminocarbene–palladium complexes as easily accessible and convenient catalysts for copper-free Sonogashira reactions

Two easily accessible hydrazinoaminocarbene complexes of Pd(II) are shown to be efficient catalysts for copper-free Sonogashira cross-couplings of a variety of aryl iodides with aryl- and alkylalkynes under mild conditions, in ethanol as the solvent and using potassium carbonate as the base. The reactions were carried out with 0.05 mol % of the catalysts which demonstrated exceptional stability in the solid state and in ethanol. Protection from air is not needed. Disubstituted acetylenes were synthesized by the general procedure on up to a gram scale and the yields were 80–98%.     

Synthesis of novel 8-(het)aryl-6H-pyrano[4′,3′:4,5]thieno[3,2-b]pyridines by 6-endo-dig cyclization of Sonogashira products and halolactonizations with Cu salts/NXS. Preliminary antitumor evaluation

Novel 8-(het)aryl-6H-pyrano[4′,3′:4,5]thieno[3,2-b]pyridines were prepared in good to high yields by a tandem one-pot procedure of Sonogashira coupling and 6-endo-dig lactonization from 3-bromothieno[3,2-b]pyridine-2-carboxylic acid and (het)arylalkynes. Sonogashira coupling products were also prepared from the corresponding methyl ester giving in the same reaction the corresponding 6-endo-dig compounds as minor products. The Sonogashira phenyl ester product gave cyclization with electrophiles only in low to moderate yields. Nevertheless, halolactonizations using Cu(I) or (II) salts/N-halosuccinimides (NXS) from either the phenyl ester or the carboxylic acid derivatives occurred in good to high yields. The growth inhibition potential of the compounds was evaluated using human tumor cell lines, HCT-15 (colorectal adenocarcinoma) and NCI-H460 (non-small cell lung cancer) and studies of apoptosis induction were performed for the three most promising compounds in HCT-15?cells. Two of them caused almost 40% of cell death by apoptosis when tested at their 1.5?×?GI₅₀ concentrations. The tricyclic lactone with a F atom in the meta position showed to be the most promising one.     

Stereochemical features of addition of O- and C-nucleophiles to 5-(Het)aryl-2,3-dicyano-1-ethylpyrazinium salts

Stable σ^H-adducts of O- and C-nucleophiles were obtained with cations of 5-(het)aryl-2,3-dicyano-1-ethylpyrazinium, and their structure was investigated by X-ray diffraction analysis. Analytical separation was performed of 1,2-dihydropyrazines into individual enantiomers by means of HPLC on columns with chiral sorbents.     

Donor-(π-bridge)-azinium as D-π-A+ one-dimensional and D-π-A(+)-π-D multidimensional V-shaped chromophores

Heteroaromatic cations reacted with N-heteroarylacetylenes under Sonogashira conditions to allow easy access to potential single donor D-π-A(+) and V-shaped D-π-A(+)-π-D chromophores, where the acceptor moiety A is the π-deficient pyridinium cation and the donor moiety is represented by different π-excessive N-heterocycles. The β hyperpolarizabilities were measured using hyper-Rayleigh scattering experiments and the experimental data are supported by a theoretical analysis that combines a variety of computational procedures, including Density Functional Theory (DFT) and correlated Hartree-Fock-based methods (RCIS(D)).     

Synthesis of conjugated allenes through copper-catalyzed γ-selective and stereospecific coupling between propargylic phosphates and aryl- or alkenylboronates

A Cu-catalyzed γ-selective coupling reaction between propargylic phosphates and aryl- or alkenylboronates afforded aryl- or alkenyl-conjugated allenes. The reaction showed excellent functional group compatibility in both the propargylic substrates and the boronates. The reaction of an enantioenriched propargylic phosphate proceeded with excellent chirality transfer with 1,3-anti stereochemistry to give axially chiral aryl- and alkenylallenes.     

Divergent synthesis and optoelectronic properties of oligodiacetylene building blocks

A new and divergent synthetic route to oligodiacetylene (ODA) building blocks has been developed via Sonogashira reactions under a reductive atmosphere. These central building blocks provide a new way for rapid preparation of long ODAs. In addition, we report on their optoelectronic properties which are dependent on their end cap. Finally, the formation of their radical cations, and their optical properties and reactivity towards nucleophiles are investigated.     

Efficient catalyst for the Suzuki-Miyaura coupling of potassium aryl trifluoroborates with aryl chlorides

Palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of aryl- and heteroaryl chlorides with potassium aryl- and heteroaryltrifluoroborates have been accomplished with the supporting ligand S-Phos in good to excellent yield. Hindered biaryls and substrates containing a variety of functional groups can be prepared. Suzuki-Miyaura couplings of a 3-pyridyl boron-based nucleophile with aryl- and heteroaryl chlorides proceed in good to very good yield. [reaction: see text]     

Sonogashira反应研究的最新进展

对Sonogashira反应的最新研究进展作了综述. 详细地介绍了Sonogashira 反应的最新优化、联串化、绿色化以及非Pd催化的Sonogashira反应等, 同时还综述了Sonogashira反应的机理研究.     

Palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of potassium aryl- and heteroaryltrifluoroborates

An extended study of the reactivity of potassium aryl- and heteroaryltrifluoroborates in Suzuki-Miyaura cross-coupling reactions is presented. The coupling of aryl- and electron-rich heteroaryltrifluoroborates with aryl and activated heteroaryl bromides proceeds readily under ligandless conditions. When deactivated aryl- and heteroaryltrifluoroborates are coupled with aryl and heteroaryl bromides and chlorides, a low loading (0.5-2%) of PdCl(2)(dppf).CH(2)Cl(2) efficiently catalyzes the reactions. Under either condition, reactions can generally be carried out in an open atmosphere.     

Oxidative condensations to form benzimidazole-substituted potassium organotrifluoroborates

A library of benzimidazole-substituted potassium organotrifluoroborates was prepared via the condensation of various potassium formyl-substituted aryl- and heteroaryltrifluoroborates with aromatic 1,2-diamines under oxidative conditions. The efficient Suzuki-Miyaura cross-coupling of products thus formed to various aryl and heteroaryl bromides was achieved in good yields. The method allows the facile preparation of benzimidazole-containing triaromatic products in two steps from simple potassium formyl substituted aryl- or heteroaryltrifluoroborates.     

Synthesis of novel aryl-1,2-oxazoles from ortho-hydroxyaryloximes

The reaction of ortho-hydroxyaryloximes with p-toluenesulfonyl chloride in the presence of an amine base efficiently generates the corresponding aryl-1,2-oxazole. Investigations revealed that solvent polarity greatly affected the rate of the reaction with faster rates observed in more polar solvents. The reaction proceeds to completion in only a few minutes in acetonitrile at room temperature, and the synthesis of four novel aryl-1,2-oxazoles is presented.     

Decorating nickel phthalocyanine periphery by aryl-1,3,4-oxadiazole pendants: synthesis,characterization, and conductivity studies

We have decorated nickel phthalocyanine (NiPc) periphery by four different aryl-[1,3,4]-oxadiazole pendants. Introduction of aryl-[1,3,4]-oxadiazole pendants into the NiPc core results in improved thermal stability, fine-tuning of the position of the Q-band with decrease in band gap, indicating effective electronic communication between the two different ring systems with NiPc core. The magnitude of DC electrical conductivity for aryl-[1,3,4]-oxadiazole-substituted NiPcs 3a–3d is found to be ～10⁵ times higher than the parent NiPc (1). The temperature-dependent DC conductivity studies reveal semiconducting nature of the newly synthesized NiPc compounds with significant decrease in thermal activation energy (ΔE) compared to parent NiPc.     

Efficient ligandless palladium-catalyzed Suzuki reactions of potassium aryltrifluoroborates

[reaction: see text] The ligandless palladium-catalyzed Suzuki cross-coupling reaction of potassium aryl- and heteroaryltrifluoroborates with aryl- or heteroaryl halides or triflates proceeds readily with very good yields. The cross coupling can be effected in methanol or water, in the open air, using Pd(OAc)(2) as a catalyst in the presence of K(2)CO(3). A variety of functional groups are tolerated.     

Reaction of 3-aminoquinoline-2,4-diones with nitrourea. Synthetic route to novel 3-ureidoquinoline-2,4-diones and imidazo[4,5-c]quinoline-2,4-diones

1-Unsubstituted 3-alkyl/aryl-3-amino-1H,3H-quinoline-2,4-diones react with 1-substituted and 1,1-disubstituted ureas in boiling acetic acid to give 2,6-dihydro-imidazo[1,5-c]quinazoline-3,5-diones. In contrast, the reaction of these amines with nitrourea in dioxane affords novel 3-alkyl/aryl-3-ureido-1H,3H-quinoline-2,4-diones or 9b-hydroxy-3a-alkyl/aryl-3,3a,5,9b-tetrahydro-1H-imidazo[4,5-c]quinoline-2,4-diones, which can smoothly be dehydrated to 3a-alkyl/aryl-3,3a-dihydro-5H-imidazo[4,5-c]quinoline-2,4-diones. All three types of products can be converted to 2,6-dihydro-imidazo[1,5-c]quinazoline-3,5-diones by refluxing in acetic acid.     

Pyrazolyl-functionalized 2-methylimidazolium-based ionic liquids and their palladium(II) complexes as recyclable catalysts

A series of pyrazolyl- and 3,5-dimethylpyrazolyl-functionalized 2-methylimidazolium-based salts have been prepared through neat reactions of 1-pyrazolylmethylene-2-methylimidazole and 1-(3,5-dimethylpyrazolylmethylene)-2-methylimidazole with alkyl or polyfluoroalkyl iodides or 1-bromohexane, followed by anion exchange with LiN(SO2CF3)2 or KPF6. Their thermal properties were determined by DSC and TGA. Most of the bis(trifluoromethanesulfonyl)amide salts are room temperature ionic liquids. The influence of anions and of the structural variation in the 2-methylimidazolium-based cations on the physicochemical properties is discussed. These salts reacted easily with palladium(II) chloride to generate mononuclear palladium ionic liquid complexes. The catalytic activity and recyclability of the palladium complexes in the corresponding ionic liquids were preliminarily examined using Heck, Suzuki and Sonogashira cross-coupling reactions in the absence of phosphine ligands.     

Simple palladium(II) precatalyst for Suzuki-Miyaura couplings: efficient reactions of benzylic, aryl, heteroaryl, and vinyl coupling partners

trans-PdBr(N-Succ)(PPh3)2 (1) is a universally effective precatalyst for Suzuki-Miyaura cross-couplings of benzylic halides with aryl- or heteroarylboronic acids. Substituted aryl halides and halogenated cyclic enones can be cross-coupled with aryl- or vinylboronic acids in excellent yields. Catalyst recycling is also demonstrated.     

Ultrasound-assisted synthesis of Z and E stilbenes by Suzuki cross-coupling reactions of organotellurides with potassium organotrifluoroborate salts

Palladium (0)-catalyzed cross-coupling reactions between potassium aryl- and vinyltrifluoroborate salts and aryl- and vinylic tellurides proceeds readily to afford the desired stilbenes in good to excellent yields. Stilbenes containing a variety of functional groups can be prepared.